Impaired hemodynamics of the patella in patients with patellofemoral pain: A case–control study

Abstract

Purpose: According to the homeostasis model, patellofemoral pain (PFP) arises as a consequence of disturbed homeostasis of anterior structures of the knee due to vascular insufficiency. Near-infrared spectroscopy (NIRS) allows to measure changes of concentrations (µmol/cm2) of (de)-oxygenated hemoglobine (HHb and O2Hb). The aim was to study differences in patellar hemodynamics between patients and healthy controls. Methods: Hemodynamics of patients (n = 30 [female = 20, age = 21.5, BMI = 22.9]) and controls (n = 30 (female = 18, age = 21.4, BMI = 22.4]) were evaluated for two activities (‘Prolonged Sitting’ and ‘Stair Descent’). Blinding for health status was implemented. Results: During ‘Prolonged Sitting’, PFP patients exhibited smaller decreases in mean changes for HHb (PFP [M = −1.5 to −1.9], healthy controls [M = −2.0 to −2.3]) and O2Hb (PFP [M = −2.0 to −3.2], healthy controls [M = −3.4 to −4.1]). However, these differences were statistically non-significant (p = 0.14–0.82 and p = 0.056–0.18, respectively). Conversely, for ‘Stair Descent’, PFP patients showed statistically significant smaller decreases in mean changes for HHb (PFP [M = −1.9, SD = 1.8], healthy controls [M = −2.5, SD = 1.7], p = 0.043) and O2Hb (PFP [M = −3.2, SD = 3.2], healthy controls [M = −4.9, SD = 2.7], p = 0.004). Conclusions: The differences suggest potential impairment in patellar hemodynamics in PFP patients, providing support for the homeostasis model. Evidence-based treatment strategies targeting patellar hemodynamics should be further refined and subjected to evaluation in clinical trials. Level of Evidence: Level III.